Lately I've been trying to think about aging, and one aspect of the topic is personal identity. Do we remain the same individuals even as we radically change in old age? Accounts of personal identity can find it either easy or difficult to say we do. Sometimes a view has to "just say no" and in other cases it takes a lot of fancy foot work to be able to say yes. In the fancy foot work category is the new account of personal identity in Marya Schechtman's book Staying Alive.
The general idea of the book is that A and B are the same person just in case A and B have the same "person life." A person life is the kind of life that we live--a life that involves things like wearing clothes, having names instead of numbers, having interests and friendships, and so on. If Bert, at 90, is living the same person life as Bertie at 10, then they are the same person. In fact, Bert could even be the same person as a newborn or even a fetus. The critical concept is "same life," which is supposed to illuminate when we're looking at one person, though possibly at two times, or we're looking at two.
Living the same life is not precisely analyzed in the book, but Schechtman is clear that it does not require going on with the same body. If my cerebrum were transplanted into a whole new body, my life could continue, she says, and I would remain in existence. It's the ongoing person life that makes me me.
Now the plot thickens. Fetuses and newborns don't really do much to live a person life, and sometimes very old people don't do much either. This is one of the places where Schechtman's book is most provocative. She says, in effect, that it can take a village to make a person. A very old person with dementia and other disabilities may only continue living a person life thanks to family members and support staff. The elements that make a life distinctively human may have no meaning to the individual--they may be provided entirely by others. That dependence doesn't make a person life stop. Even a person in a persistent vegetative state can continue not just an organismic life, but their person life, thanks to the support of others.
Likewise, she thinks, at the other end of life. A newborn doesn't live a person life except thanks to his parents and other helpers. The power of others is so great, says Schechtman, that they can even give a fetus a person life--by naming the baby, thinking about his future, etc. If you've already readied the nursery, bought clothing, and started to think of her as being at the start of a person life, then your child's life has started.
I find the person life view at least intriguing, with respect to old age, but manifestly problematic with respect to the beginning of life. One thing Schechtman doesn't say much about is cultural and personal variability when it comes to fetal and newborn life. This is dealt with in fascinating detail by David Lancy, in The Anthropology of Childhood: Cherubs, Chattel, Changelings. As the title hints, there is amazing variability, across cultures, and even within cultures, in the way fetuses and newborns are treated. In some cultures, they tend to be given person lives from the beginning of pregnancy, and in others the onset of a person life is delayed, so that the start of life is years after birth. That strikes me as problematic for Schechtman, since I can't get myself to believe that persons start existing at different times depending on things so variable and extrinsic to them.
The Human Animal) arise here. Does the fetal pre-person just go out of existence, being replaced by the person? Weird idea! If, on the contrary, the fetus continues to exist, but starts "constituting" a person, there's a puzzle about whether the pivotal property--living a person life, on Schechtman's view--is possessed by both the fetus and the person or just the person. Both answers are unpalatable.
OK, let's get on with the two headed boy (or actually, girl). Here's a case that seems problematic for Schechtman--a case where it seems clear that two persons exist, but on her view just one person exists, because there's just one person life. The case comes from a This American Life Episode called "Switched at Birth." In 1951 Mary Kay Miller gave birth to a baby under general anesthesia. Another woman, Kay McDonald, gave birth in the same room shortly afterwards, and the babies were mistakenly switched. When she got home, Mary Kay wondered whether she had the right baby, because the baby she brought home was two pounds heavier than at birth. However, her husband didn't want to pursue the issue, so she put it out of her mind. They raised the baby they took home and the McDonalds raised the baby they took home. They had no idea there was any problem.
Now take the "two headed babies": MarthaSue, the baby who started off in one mother's uterus plus the baby who went home with her; and SueMartha, the baby who started off in the other mother's uterus plus the baby who went home with her. Intuitively, MarthaSue and SueMartha are are just concatenations--there is no one person made out of two organisms, in the way the names suggests. But on the person life view, it seems to me there might be. We can easily imagine each set of parents endowing the fetus with a life, long before birth. Considering that at this point it's the parents doing the endowing, the person life that starts with a fetus seems to continue in the body of the baby who comes home--a different organism. That's the upshot of putting person-creating power in the hands of parents, instead of seeing it as residing in organisms themselves. It becomes all important what they think about their child's lifespan, and these parents thought of the life that started before birth as continuing in the body of the child they brought home.
My gut feeling: personal identity is not as social and extrinsic as that. On the other hand, it does seem interesting and important how "the village" helps personhood along, both at the beginning of life and at the end. There's something to that idea.